add method
Sends data on the WebSocket connection. The data in data must be either a String, or a List
Implementation
@override
Future<void> add(Object data) async {
if (_isClosed) return Future<void>.error(const WSClientClosed());
await _eventQueue.push('add', () => _client.add(data));
WebSocketMetricsManager.instance.sent(this, data);
}